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Speaker 1: Hey, hoorra, I have a visual challenge for you.

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Speaker 2: Ooh, I'm qualified for that.

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Speaker 1: So I'm thinking about how babies always seem cute. You know, kittens, puppies,

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Speaker 1: even little baby plants are cute.

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Speaker 2: Yeah, Candy and I, babies are cute.

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Speaker 1: So I'm wondering if we can apply to some of

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Speaker 1: that visual arts logic to physics. Can you think of

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Speaker 1: a way to make like a baby star look cute?

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Speaker 2: Oh? I thought you were gonna ask me if I

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Speaker 2: can make physicists look cute. The answer is no, that's impossible.

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Speaker 2: But what do you mean like the stars of babies.

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Speaker 1: Well, we say that they're born in stellar nurseries, and

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Speaker 1: we have you know, lullabys like Twinkle Twinkle, Little Star.

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Speaker 1: So how would we draw a baby star to make

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Speaker 1: it look cute?

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Speaker 2: Well, you know, maybe you can give it like a

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Speaker 2: plasma ribbon or have a burp little cute solar wind burps.

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Speaker 2: I wonder if that would make people go, oh, that

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Speaker 2: would be the plan. Or we should come up with

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Speaker 2: like an internet meme like baby star, baby Star Star

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Speaker 2: Star Sistar Star baby.

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Speaker 1: Star sounds like a viral TikTok video.

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Speaker 2: Bam, We're billionaires. Hi, I'm more ham Mad, cartoonist and

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Speaker 2: the creator of PhD comics.

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Speaker 1: Hi I'm Daniel. I'm a particle physicist and a professor

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Speaker 1: at UC Irvine, and I think the universe is beautiful,

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Speaker 1: but I'm not sure I would call it cute. Hmmm.

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Speaker 2: It's pretty cute, right, the way it all works together,

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Speaker 2: that's pretty like cute, but maybe like in an ironic sense,

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Speaker 2: like generalativity.

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Speaker 3: Oh that's cute. Oh like clever, yeah, clever. Yeah, yeah,

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Speaker 3: it's clever. I think it's more grand though, and dramatic

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Speaker 3: than cute. Cute makes me feel like we're minimizing it somehow.

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Speaker 2: M see what you mean. Yeah, but still it Maybe

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Speaker 2: it can be grand and cute. It can be cute

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Speaker 2: in a grand way.

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Speaker 1: Does anybody ever look at the Grand Canyon and say, ooh,

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Speaker 1: what a cute canyon.

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Speaker 2: Well, it maybe depends on your size, Like if you're

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Speaker 2: a giant, maybe the Grand Canyon looks cute to you. Yeah,

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Speaker 2: there you go. If you're the size of a galaxy,

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Speaker 2: maybe the universe would be cuter. Hmm.

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Speaker 1: So maybe astronomy and cosmology is grand and particle physics

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Speaker 1: is cute.

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Speaker 2: Yeah, Or maybe you're just too small.

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Speaker 1: I'm just trying to get you to call me cute.

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Speaker 1: That's the whole game here. I see it's not going

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Speaker 1: to happen though.

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Speaker 2: Oh that's cute, Daniel, right, success, But anyways, Welcome to

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Speaker 2: our podcast Daniel and Jra Explain the Universe, a production

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Speaker 2: of iHeartRadio.

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Speaker 1: In which we try to avoid getting too cute and

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Speaker 1: do dig deep into the mysteries of the universe. We

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Speaker 1: want to understand all of the grand questions of reality.

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Speaker 1: How does it all work, where does it all come from,

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Speaker 1: how big is it? And fundamentally, what are the rules

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Speaker 1: that decides what happens and what does not happen. We

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Speaker 1: cast our minds out into the universe to look at

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Speaker 1: all the crazy things that we observe black holes and

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Speaker 1: stars and galaxies and tiny little quirks and photons, to

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Speaker 1: try to understand how all of it comes together to

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Speaker 1: make our universe.

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Speaker 2: That's right, because it is a pretty adorable and cuggly universe.

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Speaker 2: And every episode we try to have a little meat

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Speaker 2: cute here between the universe and your mind.

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Speaker 1: We want you to look at the universe and understand

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Speaker 1: something about how it works and go aw, that's so cute,

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Speaker 1: or at least that's so clever.

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Speaker 2: It's a fine line between awe and awe, and you, well,

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Speaker 2: then you got to change one of the valves.

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Speaker 1: But it's true that we often look at the processes

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Speaker 1: in the universe or discover something that's happening out there,

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Speaker 1: and even if we don't say awe, we might say wow,

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Speaker 1: that's awesome, that's cute some at least, I mean the

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Speaker 1: sheer power and the magnitude of what's going on, like

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Speaker 1: at the heart of our star, or understanding the forces

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Speaker 1: involved in the energy scales of the formation of the

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Speaker 1: Solar system, or the black holes at the centers of galaxies.

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Speaker 1: It really makes you feel tiny. It makes you understand

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Speaker 1: that the universe operates at these grand scales that are

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Speaker 1: almost beyond our ability to understand, and yet here we

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Speaker 1: are on this tiny little rock trying desperately to understand it.

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Speaker 2: It's a pretty amazing universe, and one thing I think

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Speaker 2: a lot of people forget is that it's still happening

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Speaker 2: right now. I think to think of the universe as

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Speaker 2: super duper old and establish and fix out there in

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Speaker 2: the cosmos, but actually there's a lot going on right now,

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Speaker 2: including new stars being born.

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Speaker 1: Yeah, when you look up at the night sky, you think, oh,

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Speaker 1: this is the night sky. It's always been the night sky.

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Speaker 1: My great grandparents and my great Kirkirkirk grekork great grandparents

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Speaker 1: saw the same stars, and my grandchildren will see the

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Speaker 1: same stars. It feels immutable, feels unchanging. But we know

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Speaker 1: that the cosmos are dynamic. We know that things are

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Speaker 1: changing up there. It just happens sort of over deep

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Speaker 1: time instead of over the sort of minutes and days

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Speaker 1: and months that we are used to. But if you

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Speaker 1: look in the right places at the right times, you

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Speaker 1: can still see stuff happening and learn something about how

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Speaker 1: the universe works.

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Speaker 2: Yep, it happens over long stretches of times. But it's

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Speaker 2: also happening right now as we speak. There are probably

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Speaker 2: countless stars being born right now. There's a bunch of

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Speaker 2: baby stars out there in the night sky.

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Speaker 1: That's right. Stars are being born in stellar nurseries, and

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Speaker 1: stars are dying, exploding in supernovas, or just fizzling out.

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Speaker 1: Stars do not last forever, And what I think is

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Speaker 1: interesting is that we give them a life cycle as

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Speaker 1: if stars were alive. You know, they have a process

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Speaker 1: of formation and then dissipation or ending. But they're never

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Speaker 1: like life in the sense of the bile and just

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Speaker 1: think about it. But we talk about them being born.

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Speaker 2: And how do you know, Daniel, have you asked the star?

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Speaker 1: I have actually shouted at the Sun many times and

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Speaker 1: never heard a response.

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Speaker 2: Well, that could just be you, not the star.

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Speaker 1: Maybe I just don't speak sun ease or stella.

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Speaker 2: You need to get the right email address or a

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Speaker 2: toll freak number to call.

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Speaker 1: Maybe my accent is just terrible and I can't understand

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Speaker 1: what I'm saying.

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Speaker 2: Oh right, maybe you need to speak star ease.

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Speaker 1: In order to spark a conversation.

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Speaker 2: Yeah, and illuminating discussion about the life of stars.

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Speaker 1: But the formation of stars, how they operate internally, how

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Speaker 1: they die, These are still big questions in science. We

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Speaker 1: look out there in the universe and we see regions

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Speaker 1: where stars are being formed rapidly, in regions where galaxies

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Speaker 1: have quenched, where they are no longer making stars. This

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Speaker 1: is a really important thing to understand in the universe

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Speaker 1: because formation of stars is pretty basic to creating the

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Speaker 1: conditions for life. If we'd like to understand our very

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Speaker 1: very long term future in the universe, we need to

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Speaker 1: understand if more stars are going to be made for

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Speaker 1: us to eventually move to when ours fizzles out.

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Speaker 2: Yeah, there are a lot of amazing ways that stars

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Speaker 2: are being born out there, and every day we're also

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Speaker 2: discovering new ways that stars might be born out there.

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Speaker 2: And so today on the podcast, we'll be tackling the

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Speaker 2: question can black holes form stars?

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Speaker 1: I think this is a little bit of a rehabilitation

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Speaker 1: of the reputation of black holes.

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Speaker 2: Oh whoa, whoa, whoa, you just went deep there? What

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Speaker 2: what's wrong with black holes? Do they get canceled in culture?

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Speaker 1: I mean they're seen as destructive, right. They're like the

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Speaker 1: vacuum cleaners of the universe. They slop stuff up and

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Speaker 1: disappear it. They're not usually talked about. It's like part

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Speaker 1: of a process of rebuilding. They're like the end point

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Speaker 1: of the universe. Everything will finally end up inside some

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Speaker 1: vast black hole, separated by infinitely empty space. But instead

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Speaker 1: it might turn out that black holes have some positive

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Speaker 1: sides to it. Well.

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Speaker 2: As a person who cleans up the dishes and washes

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Speaker 2: them every night in my house, I would say that,

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Speaker 2: you know, props of the whoever is out there in

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Speaker 2: the universe cleaning things up and vacuuming all the all

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Speaker 2: the dirty dishes.

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Speaker 1: I mean, the universe is a bit of a mess,

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Speaker 1: but I don't want to see the whole thing just

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Speaker 1: like sucked up into a giant black hole. That would

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Speaker 1: seem kind of dull. You know. Sometimes you got to

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Speaker 1: embrace the mess.

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Speaker 2: That black holes were exciting, but you don't know what's

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Speaker 2: going on. Maybe there's a big party inside the black hole.

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Speaker 1: Maybe they're actually just a big mess. You know, we

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Speaker 1: thought they're cleaning things up, but it's sort of like

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Speaker 1: that closet you shove stuff in and if you went inside,

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Speaker 1: you'd be like, oh, oh no, this is a disaster.

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Speaker 2: But full of amazing things.

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Speaker 1: I'm sure that's right. You could learn so much about

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Speaker 1: the universe or that family by opening their closet slash

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Speaker 1: black hole.

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Speaker 2: But this is an interesting question, I think because we

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Speaker 2: don't often associate black holes with the formation of stars,

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Speaker 2: like usually maybe think of stars forming out there in

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Speaker 2: space and the emptiness of space in a big dust cloud.

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Speaker 2: But to think that it could maybe be born from

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Speaker 2: a black hole, or buy a black hole, or through

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Speaker 2: a black hole, it's pretty interesting to think.

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Speaker 1: About Yeah, it's a really fun counterintuitor topic, and I

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Speaker 1: recently read a paper exploring this and I thought this

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Speaker 1: would be fun to talk about.

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Speaker 2: Well, as usual, we were wondering how many people out

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Speaker 2: there had thought about the possibility of stars being born

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Speaker 2: from a black hole or buy a black hole, So

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Speaker 2: as usual, Daniel went out there into the wilds of

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Speaker 2: the Internet to ask people do you think black holes

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Speaker 2: can form from stars?

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Speaker 1: So thanks very much to the denizens of the wild

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Speaker 1: Internet who answer these questions for us. Everybody is welcome

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Speaker 1: to do so, don't be shy. Write to me two

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Speaker 1: questions at Daniel and Jorgeedon and I'll set you up.

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Speaker 2: Here's what people had to say.

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Speaker 4: I feel like they could definitely form some stars. You know,

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Speaker 4: they're stripping some material off of some stars, probably move

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Speaker 4: some material from that star over to this spot and

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Speaker 4: maybe becomes enough material to make a star.

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Speaker 2: Well maybe if they only if only hydrogen falls in

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Speaker 2: and they radiate away enough, most become a stag in.

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Speaker 5: I don't think that black holes can form stars directly,

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Speaker 5: but maybe they can form them indirectly, you know, since

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Speaker 5: they have such a strong pull of gravity, I'm sure

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Speaker 5: they have influences on the molecular clouds around them, and

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Speaker 5: maybe they can help stars form that way.

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Speaker 2: All right, some interesting possibilities here. Two out of three

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Speaker 2: people in the Internet think it's popple.

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Speaker 1: So boom, that's it. Question settled.

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Speaker 2: That's right. We all know how well polls work on

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Speaker 2: the Internet.

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Speaker 1: Hey, this was done by a scientist, so therefore it's scientific. Right.

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Speaker 2: Sure, that's cute.

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Speaker 1: It's not pretty, but it might be cute.

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Speaker 2: Yeah. So some people here thought that it wasn't possible

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Speaker 2: for stars to be born from black holes, and some

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Speaker 2: people thought maybe, like enough hydrogen falls in and or

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Speaker 2: it gets shut out, it maybe can become a star again.

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Speaker 1: Yeah, there's some really creative problem solving here. I love

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Speaker 1: hearing people use the physics in their minds to try

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Speaker 1: to tackle a new question. I mean, that's really what

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Speaker 1: physics is all about. It's a little set of tools

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Speaker 1: to try to answer questions about the universe. And everybody

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Speaker 1: who's doing that out there in their heads is doing physics.

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Speaker 1: You're all physicists deep down. I mean that as a compliment,

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Speaker 1: of course.

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Speaker 2: You mean, you're all cute on the outside, but physicists

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Speaker 2: on the inside. Is that what you're saying, which means

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Speaker 2: you're clever all the way through. All right, Well, let's

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Speaker 2: dig into this possibility of black holes forming stars, and

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Speaker 2: let's start with the basics. Let's talk about what a

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Speaker 2: black hole actually is.

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Speaker 1: So, boy, do I wish I knew what a black

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Speaker 1: hole actually is. You know, we tend to think of

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Speaker 1: it as like the endpoint of the life of a star.

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Speaker 1: You start with a big blob of stuff and gravity

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Speaker 1: pulls it together and you form a star and it

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Speaker 1: burns for a long time, and in burning, it helps

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Speaker 1: prevent further gravitational collapse. You know, gravity is always tugging

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Speaker 1: on this stuff. It's always pulling one bit of hydrogen

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Speaker 1: closer to another bit of hydrogen. But gravity is pretty weak,

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Speaker 1: so it has to sort of wait until all the

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Speaker 1: other forces have stopped working in the opposite direction. When

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Speaker 1: a star is burning, it's pushing energy out. It's like

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Speaker 1: blowing radiation out, and that prevents the star from collapsing further.

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Speaker 1: But that fire can't last forever, and eventually it burns

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Speaker 1: out and then gravity takes over and the whole thing collapses.

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Speaker 1: If you have enough mass and that initial clump of stuff,

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Speaker 1: you know, maybe more than forty times the mass of

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Speaker 1: our Sun, then it can collapse and form a black hole,

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Speaker 1: which is essentially the gravitational endpoint. When gravity's collapsed, everything

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Speaker 1: to be so dense that space is twisted and, as

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Speaker 1: you'd like to say, forms a hole, a place where

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Speaker 1: anything that goes in can never come out.

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Speaker 2: Now, just to tear, Not all stars end up. Dye

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Speaker 2: is a black hole, right, It has to be a

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Speaker 2: certain kind of star, and even if it does collapse,

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Speaker 2: they don't all form black holes, right. In fact, it's

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Speaker 2: kind of rare, right, Most stars just keep aching and

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Speaker 2: lead a long and pretty unexciting demise.

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Speaker 1: Yeah, that's right. And the endpoint of a star is

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Speaker 1: determined almost entirely by its initial amount of mass. So

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Speaker 1: if you don't have enough mass to even burn and

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Speaker 1: start fusion, then we call you like a brown dwarf

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Speaker 1: for a failed star. If you're a low mass star,

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Speaker 1: like less than eight times the mass of our Sun,

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Speaker 1: you don't form a black hole. It'll become a red giant,

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Speaker 1: and then maybe like a planetary nebula, at the core

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Speaker 1: will be something like a white dwarf, which will last

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Speaker 1: for a long time and eventually cool into a black dwarf,

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Speaker 1: but will not form a black hole. Only the larger

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Speaker 1: stars that have the capacity to become a black hole.

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Speaker 1: So bigger than like eight or ten times the mass

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Speaker 1: of our Sun, you end up as a red super giant.

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Speaker 1: And then you get these core collapse supernova And if

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Speaker 1: it has enough mass, if it started out with more

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Speaker 1: than forty times the mass of the Sun, it's almost

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Speaker 1: certainly going to end up being a black hole. But

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Speaker 1: you're right, those are rare because the most common type

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Speaker 1: of star in the universe are not the massive stars.

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Speaker 1: They're the little red dwarfs, stars that are cooler and

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Speaker 1: smaller than our star. Because the smaller the star, the

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Speaker 1: colder it is at it's core, and so the dimmer

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Speaker 1: it burns. So very big stars end up as black holes,

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Speaker 1: but they also don't last very long. Very small stars

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Speaker 1: are cooler but last longer. The smallest ones can burn

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Speaker 1: for billions and billions, maybe even trillions of years.

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Speaker 2: Yeah, like you said, it's rare, and only if it

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Speaker 2: has enough mass. But even if it has a lot

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Speaker 2: of mass and it collapses, well, I guess we're not

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Speaker 2: super duper sure that a black hole will form, right,

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Speaker 2: Like they could also form, like you said before, a

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Speaker 2: neutron star maybe, or we actually don't know. We've never

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Speaker 2: seen a black hole born out of a star.

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Speaker 1: So if you have like more than ten times the

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Speaker 1: mass of the Sun but less than forty times, you're

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Speaker 1: likely to make a neutron star, which is a very

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Speaker 1: very dense object filled with neutrons. But those neutrons are

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Speaker 1: resisting gravitational collapse. They're preventing it from becoming a black hole.

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Speaker 1: If it happens to eat some more mass and then

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Speaker 1: get over the mass threshold, then it can collapse into

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Speaker 1: a black hole. But if you have enough mass, it's

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Speaker 1: almost inevitable to become a black hole, at least if

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Speaker 1: black holes even exist. As you said, we're not even

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Speaker 1: really sure that black holes are black holes. The way

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Speaker 1: we think about them, we have a description of them

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Speaker 1: in general relativity, which uses a pure gravitational description and

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Speaker 1: ignores all the quantum mechanics and says that gravity will

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Speaker 1: pull everything together to this tiny dot a singularity at

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Speaker 1: the heart of these black holes and form an event

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Speaker 1: horizon around them. That's the general relativity view, and for

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Speaker 1: a long time that was basically the only idea out

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Speaker 1: there that could explain what we were seeing in the universe.

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Speaker 1: We saw these very dark, very dense blobs of matter

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Speaker 1: that we could only explain with black holes. Now though

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Speaker 1: we have other ideas. Maybe these are fuzzballs, maybe these

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Speaker 1: are dark stars, maybe these are something else entirely. Last

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Speaker 1: week we talked about balls of vacuum energy that could

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Speaker 1: look like black holes, So there's been a real flourishing

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Speaker 1: of ideas for what these things actually are.

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Speaker 2: Yeah, and also not all black holes come from stars,

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Speaker 2: right like, there are some black holes that may be

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Speaker 2: formed at the beginning of the universe, right from in

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Speaker 2: the Big Bang. And there's also kind of a mystery

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Speaker 2: how some black holes out there form, right like some

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Speaker 2: of the big ones in the middle of galaxies. Were

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Speaker 2: not quite sure how those started.

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Speaker 1: It's definitely a mystery how black holes the hearts of

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Speaker 1: galaxies started. We tend to have two categories of black holes.

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Speaker 1: The ones that came from like an individual star like

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Speaker 1: we just talked about, and then these mammoth black holes

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Speaker 1: we call them super massive black holes that the hearts

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Speaker 1: of galaxies that can have masses of millions or billions

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Speaker 1: of times the mass of the Sun. And these we

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Speaker 1: think are black holes in the same category as other things,

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Speaker 1: although some theories say there's something totally different. But you're right,

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Speaker 1: we don't understand how they got so big. If you

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Speaker 1: look back into the deep history of the universe, we

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Speaker 1: can see galaxies forming in like the first billion or

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Speaker 1: two billion years already having huge black holes at their centers,

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Speaker 1: and we don't understand how they got to be so big.

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Speaker 1: One theory, as you said, is prime ordial black holes,

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Speaker 1: that maybe black holes were made during the Big Bang,

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Speaker 1: before there actually even was matter, black holes were made,

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Speaker 1: and they may have served as like seeds for these

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Speaker 1: supermassive black holes. That's just one idea, but it's definitely

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Speaker 1: a big question mark how these black holes at the

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Speaker 1: hearts of galaxies formed. But you know, we have seen

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Speaker 1: black holes like in the act of feeding. Black holes

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Speaker 1: don't just have to form from like their initial star.

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Speaker 1: They can later on gobble up other stars and get bigger.

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Speaker 2: Well, So it's kind of like a weird cycle of

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Speaker 2: stellar life out there in the cosmus, right, Like some

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Speaker 2: black holes are born from stars, and then those black

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Speaker 2: holes and start eating up other stars.

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Speaker 1: Yeah, you might have a star that burns and would

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Speaker 1: eventually become a white dwarf, but it gets gobbled up

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Speaker 1: by a black hole, so it eventually ends up as

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Speaker 1: a black hole. It might not have had enough mass

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Speaker 1: to make a black hole on its own, but it

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Speaker 1: gets vacuumed up into a neighboring black hole. And this

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Speaker 1: is really dramatic and sort of amazing to watch.

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Speaker 2: Yeah, because we've actually seen this happen, right, Like we

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Speaker 2: have pictures of it.

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Speaker 1: Yeah, I've actually seen this happen. There's a great example

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Speaker 1: using X ray telescopes that watch this happen to a

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Speaker 1: black hole and another galaxy. Two hundred and fifty million

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Speaker 1: light years from Earth. There's a black hole in the

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Speaker 1: center of another galaxy. It has like ten million solar masses,

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Speaker 1: and they watched the star get too close and the

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Speaker 1: star was pulled apart by the gravity of the black

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Speaker 1: hole before it even went in. It like pulled it

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Speaker 1: apart into a long river of hot gas. Remember that

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Speaker 1: gravity does more than just tug on things. It can

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Speaker 1: also tear them apart because of the tidal forces.

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Speaker 2: Right, Because I guess the part of the star that's

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Speaker 2: closer to the black hole gets pulled faster or stronger,

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Speaker 2: and so then it starts to get stretched out, sort

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Speaker 2: of like if you're sucking up with a vacuum a

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Speaker 2: big pile of legos or something, it's going to break

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Speaker 2: up the cluster of legos.

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Speaker 1: Yeah, gravity pulls more strongly on things that are closer

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Speaker 1: to the source. And if gravity is really really powerful

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Speaker 1: and you have something big enough, then the force on

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Speaker 1: one side of it is pretty different from the force

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Speaker 1: and the other and that's effectively like gravity pulling that

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Speaker 1: thing apart. I mean, the Earth right now is pulling

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Speaker 1: on your body with a different force than it's pulling

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Speaker 1: on your head, and effectively, that's like the Earth trying

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Speaker 1: to pull the head off of your body. It's not

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Speaker 1: very powerful because Earth's gravity is pretty gentle and your

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Speaker 1: head is pretty close to your body, but if you

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Speaker 1: were a big enough object and close enough to a

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Speaker 1: very strong source of gravity, you'd be pulled apart. And

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Speaker 1: they saw this happen to a star. We've seen this

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Speaker 1: happen also to like comets that have entered the Solar System.

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Speaker 1: Common shoemaker levee got pulled apart into like twenty six

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Speaker 1: pieces by tidal forces. Anyway, this hot river of gas

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Speaker 1: was formed and then it fell into the black hole

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Speaker 1: and they could observe it due to this increase in

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Speaker 1: X ray emission from the accretion disk of the black hole.

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Speaker 1: The whole thing took like weeks to months to happen.

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Speaker 2: M that's pretty interesting. Do we have pictures of that?

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Speaker 2: Like if can you google that and find the pictures

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Speaker 2: of this star getting spaghetified?

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Speaker 1: We don't have cool images of that, unfortunately. We just

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Speaker 1: have like X ray telescope data that showed like rises

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Speaker 1: in X ray emissions as this hot gas enters the

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Speaker 1: accretion disk. We know that it happened. We could sort

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Speaker 1: of like watch it conceptionally, but we don't have like

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Speaker 1: pictures of it, and that would be awesome.

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Speaker 2: So then how do you know it's stretched down into

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Speaker 2: a long river of hot gas? You just think it

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Speaker 2: did well.

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Speaker 1: I mean, we have X ray data, and we have

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Speaker 1: X ray telescopes, but X ray telescopes don't have the

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Speaker 1: same kind of optics as like optical telescopes and the

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Speaker 1: same kind of resolution. They're more like particle detectors. You're

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Speaker 1: looking at a single stream of photons more than you're

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Speaker 1: like taking an image with high resolution.

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Speaker 2: So you're looking at like a pinpoint of an X

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Speaker 2: ray source and suddenly that X ray stars changed and

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Speaker 2: you're inferring that it means that the star got stretched out.

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Speaker 1: Yeah, exactly. And you used to see a star which

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Speaker 1: then disappeared, and you see this emission of X rays

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Speaker 1: very close to this black hole, and so you know,

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Speaker 1: there's a few steps of inference there. But people are

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Speaker 1: pretty convinced that this was a star getting eaten by

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Speaker 1: a black hole, or at least by something right, by something,

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Speaker 1: something very dense, and something very dark ended this star.

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Speaker 2: Something out there had star pasta for dinner. All right, Well,

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Speaker 2: that's a pretty quick primer on black holes, and now

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Speaker 2: let's get into how a black hole can form a star,

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Speaker 2: whether it can, and what would it mean. But first

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Speaker 2: let's take a quick break. Or we're answering the question

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Speaker 2: can black holes form stars? Now? Are these black holes

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Speaker 2: forming the stars like out of clay?

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Speaker 4: Like?

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Speaker 2: Are they molding the stars? Are they giving birth to

438
00:20:33,640 --> 00:20:36,320
Speaker 2: the stars? Are they making, you know, pulling a magic

439
00:20:36,359 --> 00:20:38,040
Speaker 2: trick making them appear out of nowhere?

440
00:20:38,200 --> 00:20:40,560
Speaker 1: Maybe they're just ordering them on Amazon like everybody else

441
00:20:40,600 --> 00:20:41,040
Speaker 1: around here?

442
00:20:41,119 --> 00:20:42,440
Speaker 2: Does that count as forming a star?

443
00:20:42,520 --> 00:20:42,720
Speaker 4: Though?

444
00:20:43,160 --> 00:20:47,439
Speaker 2: If I order order a toothpaste from Amazon, am i

445
00:20:47,520 --> 00:20:48,920
Speaker 2: making the toothpaste.

446
00:20:48,960 --> 00:20:50,800
Speaker 1: I don't know. But if I order a Christmas present

447
00:20:50,840 --> 00:20:52,560
Speaker 1: on Amazon and give it to my kids, you know,

448
00:20:52,600 --> 00:20:54,760
Speaker 1: they feel like it was from me, even if I

449
00:20:54,800 --> 00:20:55,720
Speaker 1: didn't make it myself.

450
00:20:55,760 --> 00:20:58,359
Speaker 2: Oh it's from you, but you didn't form the gift.

451
00:20:58,440 --> 00:21:01,159
Speaker 1: No, that's true. I did not build those earbuds myself.

452
00:21:01,480 --> 00:21:03,359
Speaker 2: There you go. Well, here the question is can a

453
00:21:03,359 --> 00:21:05,800
Speaker 2: black hole form a star? And I'm guessing maybe it's

454
00:21:05,880 --> 00:21:08,840
Speaker 2: like putting together some of the gas around or is it, like,

455
00:21:09,240 --> 00:21:12,440
Speaker 2: you know, is it happening when the the stuff is

456
00:21:12,480 --> 00:21:14,159
Speaker 2: falling into the black hole? What's going on here?

457
00:21:14,359 --> 00:21:16,600
Speaker 1: So so far we mostly think about black holes is

458
00:21:16,720 --> 00:21:20,399
Speaker 1: like the death of stars or eating other stars. To

459
00:21:20,480 --> 00:21:23,440
Speaker 1: understand how black holes can contribute to star formation, we

460
00:21:23,520 --> 00:21:25,280
Speaker 1: have to think a little bit and understand a little

461
00:21:25,280 --> 00:21:27,760
Speaker 1: bit about how stars are formed in the first place.

462
00:21:27,840 --> 00:21:30,280
Speaker 1: Like if you went out to build a star, You're like, oh,

463
00:21:30,359 --> 00:21:32,960
Speaker 1: Christmas is coming, I got to get my spouse something.

464
00:21:33,160 --> 00:21:34,840
Speaker 1: What should I do? I'm gonna build them a star?

465
00:21:35,000 --> 00:21:35,800
Speaker 1: How would you do it?

466
00:21:36,040 --> 00:21:36,119
Speaker 3: Right?

467
00:21:36,200 --> 00:21:38,480
Speaker 1: How do you make a star? Anyway? And it turns

468
00:21:38,520 --> 00:21:41,800
Speaker 1: out that star formation is a little bit more delicate

469
00:21:41,920 --> 00:21:45,520
Speaker 1: and difficult than you might imagine and I think all

470
00:21:45,520 --> 00:21:47,280
Speaker 1: you need is a big block of gas and eventually

471
00:21:47,359 --> 00:21:49,399
Speaker 1: gravity's going to pull it together. So you know, just

472
00:21:49,440 --> 00:21:51,919
Speaker 1: get a scoop a hydrogen, put it in space and

473
00:21:52,040 --> 00:21:55,359
Speaker 1: wait a few million years and there's your star. But

474
00:21:55,400 --> 00:21:58,800
Speaker 1: it's not so simple. You need sort of special conditions

475
00:21:58,840 --> 00:22:01,320
Speaker 1: for that gas in order to get it to collapse

476
00:22:01,359 --> 00:22:02,080
Speaker 1: and form a star.

477
00:22:02,400 --> 00:22:04,680
Speaker 2: Yeah, I know, we talked about this before. It's kind

478
00:22:04,680 --> 00:22:08,080
Speaker 2: of related to the temperature of the gas, right, and

479
00:22:08,119 --> 00:22:10,199
Speaker 2: also how much gas there is you need, like the

480
00:22:10,280 --> 00:22:11,880
Speaker 2: right amount of the right temperature.

481
00:22:12,080 --> 00:22:13,920
Speaker 1: Yeah, it depends a lot on the temperature and also

482
00:22:14,040 --> 00:22:16,879
Speaker 1: the metallicity. Remember, at the beginning of the universe, we

483
00:22:16,920 --> 00:22:19,600
Speaker 1: had basically just clouds of hydrogen. That's what was made

484
00:22:19,680 --> 00:22:21,680
Speaker 1: during the Big Bang, a little bit of helium and

485
00:22:21,720 --> 00:22:25,280
Speaker 1: a tiny little bit of heavier stuff, but almost entirely hydrogen.

486
00:22:25,560 --> 00:22:28,199
Speaker 1: So the first stars were all just hydrogen. Then the

487
00:22:28,200 --> 00:22:33,920
Speaker 1: hearts of those stars fusion makes heavier elements helium, lithium, carbon, oxygen, nitrogen,

488
00:22:33,920 --> 00:22:36,520
Speaker 1: et cetera, all that good stuff that makes up us

489
00:22:36,560 --> 00:22:38,960
Speaker 1: and ice cream and hamsters. So to form a star,

490
00:22:39,000 --> 00:22:41,000
Speaker 1: you need gas that's cold. As you said, it can't

491
00:22:41,000 --> 00:22:44,159
Speaker 1: be too hot because hot gas means the particles are

492
00:22:44,160 --> 00:22:46,520
Speaker 1: flying around at really high speeds. And you have to

493
00:22:46,520 --> 00:22:49,480
Speaker 1: remember that gravity is really really weak, so it can

494
00:22:49,600 --> 00:22:53,320
Speaker 1: only really pull together stuff if it's almost at rest.

495
00:22:53,320 --> 00:22:55,760
Speaker 1: If the gas is cold enough, you have a big

496
00:22:55,800 --> 00:22:58,720
Speaker 1: blob of hot gas, it'll just sit there forever without

497
00:22:58,800 --> 00:23:01,800
Speaker 1: forming a star. So you need that gas to be cold.

498
00:23:02,160 --> 00:23:04,439
Speaker 1: And it also depends on how much metal you have

499
00:23:04,560 --> 00:23:05,960
Speaker 1: and like how it's distributed.

500
00:23:06,200 --> 00:23:09,840
Speaker 2: Maybe not forever, Like eventually wouldn't hot the cloud of

501
00:23:09,880 --> 00:23:13,160
Speaker 2: gas cool down or eventually some of that energy might

502
00:23:13,240 --> 00:23:14,920
Speaker 2: you know, get canceled out or something.

503
00:23:15,080 --> 00:23:17,719
Speaker 1: Well, energy is concerned, right, so the energy can't just

504
00:23:17,760 --> 00:23:21,280
Speaker 1: go away and left literally by itself. I suppose it

505
00:23:21,320 --> 00:23:25,000
Speaker 1: would expand because there's empty space around it. So hot

506
00:23:25,040 --> 00:23:28,280
Speaker 1: gas will expand into empty space and that will cool

507
00:23:28,280 --> 00:23:28,680
Speaker 1: it down.

508
00:23:28,800 --> 00:23:31,080
Speaker 2: Yeah, but I guess I mean, like, wouldn't eventually the

509
00:23:31,119 --> 00:23:34,840
Speaker 2: gas particles hit each other and lose some of that energy? Right?

510
00:23:35,000 --> 00:23:37,320
Speaker 1: These clouds of gas are pretty dilute, so you can

511
00:23:37,320 --> 00:23:40,679
Speaker 1: model them as almost entirely collisionless, I'm pretty sure. So

512
00:23:40,720 --> 00:23:42,320
Speaker 1: what you really need to form a star is you

513
00:23:42,359 --> 00:23:44,119
Speaker 1: need this gas to be cold. We also need some

514
00:23:44,160 --> 00:23:46,160
Speaker 1: sort of seed, and that can come in the form

515
00:23:46,200 --> 00:23:48,760
Speaker 1: of like having a dense little blob of some metal,

516
00:23:49,040 --> 00:23:51,239
Speaker 1: you know, formed in the heart of another star and

517
00:23:51,280 --> 00:23:54,600
Speaker 1: then left out in the cosmos to seed another star,

518
00:23:55,160 --> 00:23:57,320
Speaker 1: or some sort of like shock wave sometimes like a

519
00:23:57,359 --> 00:23:59,879
Speaker 1: nearby supernova will give a little push to some of

520
00:23:59,880 --> 00:24:02,119
Speaker 1: these things and collapse them in a way that gets

521
00:24:02,119 --> 00:24:04,960
Speaker 1: gravity started. But it's got to be gentle. It can't

522
00:24:05,000 --> 00:24:07,560
Speaker 1: be too hard. If you shock these things too much,

523
00:24:07,640 --> 00:24:09,880
Speaker 1: then you're just heating up the gas. So you got

524
00:24:09,920 --> 00:24:11,800
Speaker 1: to like cool it down so it can coalesce and

525
00:24:11,840 --> 00:24:14,040
Speaker 1: give it like the right kind of nudge or give

526
00:24:14,040 --> 00:24:16,720
Speaker 1: it like the right seed to get that collapse started.

527
00:24:16,880 --> 00:24:19,119
Speaker 2: You also need the right amount of gas, right, Like,

528
00:24:19,160 --> 00:24:22,119
Speaker 2: if you have a small cloud of gas, it's going

529
00:24:22,200 --> 00:24:24,760
Speaker 2: to clump and maybe not clump and form the kind

530
00:24:24,800 --> 00:24:27,199
Speaker 2: of pressure you need to form a star. Right, You

531
00:24:27,240 --> 00:24:29,640
Speaker 2: need like a lot of gas so that you get

532
00:24:29,640 --> 00:24:32,080
Speaker 2: a big clump and then so that the clumps kind

533
00:24:32,080 --> 00:24:35,080
Speaker 2: of squeezes the stuff in the middle enough to be

534
00:24:35,240 --> 00:24:36,199
Speaker 2: ready for fusion.

535
00:24:36,440 --> 00:24:38,640
Speaker 1: Yeah, if your clumps are too small, you just get

536
00:24:38,640 --> 00:24:41,600
Speaker 1: a bunch of Jupiter's. You don't get real stars. And

537
00:24:41,680 --> 00:24:43,880
Speaker 1: the size of the clumps that tend to form does

538
00:24:43,920 --> 00:24:47,080
Speaker 1: depend on the metallicity. So in the very early universe,

539
00:24:47,119 --> 00:24:49,840
Speaker 1: we had big stars form huge clouds of hydrogen. But

540
00:24:49,960 --> 00:24:52,160
Speaker 1: later on in the universe, we had like more seeds,

541
00:24:52,240 --> 00:24:54,639
Speaker 1: more like little dots of metal in those clouds. So

542
00:24:54,680 --> 00:24:57,119
Speaker 1: you've got more stars, but they were smaller, and then

543
00:24:57,160 --> 00:24:59,800
Speaker 1: they tend to burn longer, and so they burn from

544
00:24:59,800 --> 00:25:01,920
Speaker 1: bi millions of years rather than just like a few

545
00:25:01,960 --> 00:25:04,520
Speaker 1: million years or tens of millions of years, like the

546
00:25:04,560 --> 00:25:07,640
Speaker 1: first generation of stars. So like the composition, so it's

547
00:25:07,680 --> 00:25:10,560
Speaker 1: sort of like cooking, you know, it's really dependent on

548
00:25:10,640 --> 00:25:12,920
Speaker 1: the temperature and the exact mixture of what you put

549
00:25:12,960 --> 00:25:15,320
Speaker 1: in there. You might get a bunch of really big stars,

550
00:25:15,480 --> 00:25:18,080
Speaker 1: or smaller stars, or just a bunch of jupiters, or

551
00:25:18,280 --> 00:25:21,560
Speaker 1: almost no stars at all, depending on the temperature of

552
00:25:21,600 --> 00:25:22,400
Speaker 1: your ingredients.

553
00:25:22,640 --> 00:25:25,679
Speaker 2: M All right, then that's generally how stars form. You

554
00:25:25,680 --> 00:25:28,520
Speaker 2: need a cloud of gas and then it has to

555
00:25:28,520 --> 00:25:30,199
Speaker 2: be the right conditions, has to be cold, and there

556
00:25:30,240 --> 00:25:32,359
Speaker 2: has to be a lot of it. And this happens

557
00:25:32,400 --> 00:25:34,719
Speaker 2: a lot in certain situations out there in the universe,

558
00:25:34,800 --> 00:25:36,320
Speaker 2: right like in dwarf galaxies.

559
00:25:36,480 --> 00:25:39,280
Speaker 1: Yeah, so lots of galaxies out there are forming stars,

560
00:25:39,320 --> 00:25:42,000
Speaker 1: and lots of galaxies out there are not forming stars.

561
00:25:42,080 --> 00:25:44,879
Speaker 1: We have some bigger galaxies and we have some smaller galaxies.

562
00:25:44,920 --> 00:25:47,840
Speaker 1: And when galaxies stop forming stars, we say that they

563
00:25:47,840 --> 00:25:51,160
Speaker 1: are quenched. And actually our galaxy, like the Milky Way

564
00:25:51,200 --> 00:25:55,600
Speaker 1: and Andromeda, we think are both starting to quench. They're

565
00:25:55,600 --> 00:25:59,359
Speaker 1: forming like maybe seven stars per year. The rate of

566
00:25:59,359 --> 00:26:02,240
Speaker 1: star formation in galaxies like ours is a lot less

567
00:26:02,280 --> 00:26:04,679
Speaker 1: than it was a billion years ago, for example. So

568
00:26:04,680 --> 00:26:08,040
Speaker 1: it's really interesting to look, as you say, at little galaxies,

569
00:26:08,520 --> 00:26:11,359
Speaker 1: like what we call dwarf galaxies. These are like little

570
00:26:11,400 --> 00:26:14,760
Speaker 1: mini galaxies that have not yet combined with other galaxies

571
00:26:14,800 --> 00:26:18,119
Speaker 1: in order to form mega galaxies. All the galaxies that

572
00:26:18,119 --> 00:26:19,800
Speaker 1: you see in the Milky Way, the Androma, all the

573
00:26:19,800 --> 00:26:23,200
Speaker 1: big ones are all just combinations of these little galaxies

574
00:26:23,240 --> 00:26:25,960
Speaker 1: that came together to form a big galaxy. So looking

575
00:26:25,960 --> 00:26:28,040
Speaker 1: at a dwarf galaxy is sort of like looking at

576
00:26:28,040 --> 00:26:29,119
Speaker 1: a baby galaxy.

577
00:26:29,359 --> 00:26:33,240
Speaker 2: All exactly thin, cute. You're kind of cute and fuzzy,

578
00:26:33,240 --> 00:26:33,640
Speaker 2: aren't they.

579
00:26:33,760 --> 00:26:35,919
Speaker 1: They are kind of cute and fuzzy. In fact, one

580
00:26:35,960 --> 00:26:38,119
Speaker 1: of the things that's fuzzy about them is what constitutes

581
00:26:38,160 --> 00:26:41,399
Speaker 1: a dwarf galaxy. Like some astronomers say, you know, a

582
00:26:41,440 --> 00:26:43,840
Speaker 1: few thousands to a few billions of stars can be

583
00:26:43,920 --> 00:26:46,760
Speaker 1: a dwarf galaxy. Others have a different definition. There's a

584
00:26:46,760 --> 00:26:50,760
Speaker 1: big argument about whether the large magallinic cloud, which is

585
00:26:50,800 --> 00:26:53,760
Speaker 1: a big blob of stuff orbiting the Milky Way, counts

586
00:26:53,760 --> 00:26:56,200
Speaker 1: as a dwarf galaxy or not. But there's a lot

587
00:26:56,200 --> 00:26:58,879
Speaker 1: of interesting physics happening in these dwarf galaxies. They're a

588
00:26:58,880 --> 00:27:02,280
Speaker 1: great place to learn about star formation and about black

589
00:27:02,320 --> 00:27:04,760
Speaker 1: holes and about how they might be connected.

590
00:27:05,600 --> 00:27:07,560
Speaker 2: Well, I guess, first of all, why is it the

591
00:27:07,640 --> 00:27:10,879
Speaker 2: dwarf galaxies have more stars being born than regular stars?

592
00:27:11,080 --> 00:27:14,440
Speaker 2: Are they denser? Are they just like a newer gas.

593
00:27:14,480 --> 00:27:17,200
Speaker 1: Maybe we're not exactly sure because we don't really understand

594
00:27:17,200 --> 00:27:22,200
Speaker 1: this quenching process. Some theories of why galaxies stop making stars,

595
00:27:22,200 --> 00:27:24,680
Speaker 1: and so why dwarf galaxies might still be making more

596
00:27:24,720 --> 00:27:27,159
Speaker 1: of them could be due to the black holes at

597
00:27:27,200 --> 00:27:30,280
Speaker 1: their center. These black holes don't just suck stuff up,

598
00:27:30,320 --> 00:27:33,840
Speaker 1: they also emit radiation. As they get really massive, they

599
00:27:33,880 --> 00:27:36,200
Speaker 1: generate a lot of heat in their accretion disk, which

600
00:27:36,200 --> 00:27:38,199
Speaker 1: shoots out a lot of X rays, which ends up

601
00:27:38,240 --> 00:27:41,720
Speaker 1: heating up the galaxy and preventing it from making stars.

602
00:27:41,960 --> 00:27:44,400
Speaker 1: The other thing that can stop these big galaxies from

603
00:27:44,400 --> 00:27:49,240
Speaker 1: making stars are the stars they have stars emit radiation. Also,

604
00:27:49,280 --> 00:27:52,359
Speaker 1: there's stellar wind right or super novas that from the

605
00:27:52,520 --> 00:27:55,520
Speaker 1: end of stars life cycles. These can also heat up

606
00:27:55,520 --> 00:27:58,560
Speaker 1: the stellar nurseries too much, so they're not really prime

607
00:27:58,640 --> 00:28:01,400
Speaker 1: for making stars anymore. Are too hot, and so these

608
00:28:01,480 --> 00:28:04,359
Speaker 1: dwarf galaxies don't have that as many stars and don't

609
00:28:04,400 --> 00:28:07,199
Speaker 1: have super big black holes at their hearts, so they

610
00:28:07,240 --> 00:28:09,120
Speaker 1: might be better places to make stars.

611
00:28:09,280 --> 00:28:10,879
Speaker 2: So the next time somebody asked me like, hey, are

612
00:28:10,880 --> 00:28:12,600
Speaker 2: you gonna have more kids, I can just say we're

613
00:28:12,640 --> 00:28:14,919
Speaker 2: quench we got too.

614
00:28:14,800 --> 00:28:19,360
Speaker 1: Hot, exactly. But this is sort of like the astronomical

615
00:28:19,400 --> 00:28:22,000
Speaker 1: equivalent of teenagers having kids, because now you're having like

616
00:28:22,040 --> 00:28:25,359
Speaker 1: dwarf galaxies making lots of stars in their stellar nurseries.

617
00:28:25,640 --> 00:28:28,480
Speaker 1: And there's one in particular that people are really interested

618
00:28:28,480 --> 00:28:31,000
Speaker 1: in with there's a black hole doing something very strange

619
00:28:31,040 --> 00:28:34,880
Speaker 1: and weird. It's a dwarf galaxy called Henise h e

620
00:28:35,359 --> 00:28:39,720
Speaker 1: Nize two Dash ten. It's about thirty million light years

621
00:28:39,760 --> 00:28:42,960
Speaker 1: away in the direction of the Pike Sis constellation, and

622
00:28:43,040 --> 00:28:45,040
Speaker 1: it's not that tiny. I mean, it's like a tenth

623
00:28:45,080 --> 00:28:47,160
Speaker 1: of the size of the Milky Way, but it has

624
00:28:47,240 --> 00:28:50,840
Speaker 1: a huge star formation rate. People think it's making stars

625
00:28:50,880 --> 00:28:53,680
Speaker 1: about ten times the rate of the large madell in

626
00:28:53,760 --> 00:28:55,920
Speaker 1: a cloud, even though it's about the same size.

627
00:28:56,240 --> 00:29:00,960
Speaker 2: Mmm. Interesting, So what explains why this galaxies making so

628
00:29:01,000 --> 00:29:01,560
Speaker 2: many stars?

629
00:29:01,880 --> 00:29:04,200
Speaker 1: It's not something that we understand all.

630
00:29:04,240 --> 00:29:06,320
Speaker 2: Right, then, how do black holes come into the picture?

631
00:29:06,440 --> 00:29:09,000
Speaker 2: How are we studying whether black holes can form stars?

632
00:29:09,160 --> 00:29:11,200
Speaker 1: So this dwarf galaxy is super interesting for a bunch

633
00:29:11,240 --> 00:29:13,520
Speaker 1: of reasons. One is just like to see the black

634
00:29:13,520 --> 00:29:17,080
Speaker 1: hole being formed, right, Dwarf galaxies are little galaxies, and

635
00:29:17,120 --> 00:29:19,200
Speaker 1: one question we have is like how do black holes

636
00:29:19,200 --> 00:29:21,320
Speaker 1: get formed? Do they start really big? Do they grow

637
00:29:21,400 --> 00:29:24,640
Speaker 1: with the galaxy? Are they coupled to cosmic acceleration? So

638
00:29:24,760 --> 00:29:27,120
Speaker 1: looking at the black hole, this dwarf galaxy is interesting

639
00:29:27,240 --> 00:29:28,360
Speaker 1: just from that point of view.

640
00:29:28,440 --> 00:29:30,640
Speaker 2: Oh wait, so this dwarf galaxy has a black hole

641
00:29:30,680 --> 00:29:31,080
Speaker 2: in the middle.

642
00:29:31,120 --> 00:29:33,520
Speaker 1: We know that we do think this dwarf galaxy has

643
00:29:33,560 --> 00:29:36,080
Speaker 1: a black hole. We didn't know if all dwarf galaxies

644
00:29:36,120 --> 00:29:38,280
Speaker 1: have black holes, but this one seems to have it.

645
00:29:38,400 --> 00:29:41,400
Speaker 1: The sort of distinctive radio and X ray emissions from

646
00:29:41,440 --> 00:29:44,640
Speaker 1: the heart of this dwarf galaxy that are consistent with

647
00:29:44,680 --> 00:29:48,160
Speaker 1: a black hole and like not consistent with other explanations

648
00:29:48,640 --> 00:29:52,880
Speaker 1: like X ray binaries or a supernova or something like.

649
00:29:53,040 --> 00:29:56,040
Speaker 2: At the center of this dwarf galaxy, you can tell

650
00:29:56,080 --> 00:30:00,560
Speaker 2: there's like you know, gas being maybe stretch out, and

651
00:30:00,640 --> 00:30:02,360
Speaker 2: as it falls into the black hole, you can see

652
00:30:02,400 --> 00:30:04,440
Speaker 2: signature X ray signals from it.

653
00:30:04,600 --> 00:30:07,160
Speaker 1: Yeah, exactly. You could see the radio and the X

654
00:30:07,200 --> 00:30:09,920
Speaker 1: ray emissions you would expect from the gas around the

655
00:30:10,000 --> 00:30:12,520
Speaker 1: black hole. You can also see something else. This gas

656
00:30:12,600 --> 00:30:15,479
Speaker 1: accretion disk is swirling around the black hole, and then

657
00:30:15,520 --> 00:30:19,880
Speaker 1: it's slamming into this other blob of gas basically into

658
00:30:19,920 --> 00:30:22,720
Speaker 1: a stellar nursery. So stellar nursery is just a big

659
00:30:22,800 --> 00:30:25,760
Speaker 1: blob of cold gas right where stars might be formed

660
00:30:25,760 --> 00:30:27,600
Speaker 1: if you get like the right seed to form, where

661
00:30:27,600 --> 00:30:30,680
Speaker 1: you get like the right supernova shockwave. And this black

662
00:30:30,720 --> 00:30:33,840
Speaker 1: hole is emitting a bunch of radiation and pushing gas

663
00:30:33,880 --> 00:30:37,120
Speaker 1: out also right as black holes sometimes do, and it's

664
00:30:37,160 --> 00:30:40,520
Speaker 1: slamming into this stellar nursery, but it's doing it kind

665
00:30:40,520 --> 00:30:41,160
Speaker 1: of gently.

666
00:30:41,600 --> 00:30:41,760
Speaker 2: Right.

667
00:30:41,800 --> 00:30:44,160
Speaker 1: Earlier, we talked about how super massive black holes might

668
00:30:44,240 --> 00:30:48,080
Speaker 1: stop stars from being formed by emitting really powerful radiation

669
00:30:48,160 --> 00:30:50,760
Speaker 1: that heats it up. This one is emitting radiation and

670
00:30:50,800 --> 00:30:53,320
Speaker 1: pushing the gas into the stellar nursery, but it's doing

671
00:30:53,400 --> 00:30:56,240
Speaker 1: it kind of gently. It's moving it like only a

672
00:30:56,320 --> 00:30:57,640
Speaker 1: million miles per.

673
00:30:57,400 --> 00:31:00,120
Speaker 2: Hour, a million miles per hour.

674
00:31:00,200 --> 00:31:02,760
Speaker 1: A million miles per hour, which is gentle compared to

675
00:31:02,800 --> 00:31:06,360
Speaker 1: the radiation from massive black holes, which can approach almost

676
00:31:06,360 --> 00:31:07,080
Speaker 1: the speed of light.

677
00:31:07,840 --> 00:31:09,880
Speaker 2: I'll try that excuse the next time I'm pulled over

678
00:31:09,920 --> 00:31:12,720
Speaker 2: for a speeding ticket. I was like, great, you know,

679
00:31:13,040 --> 00:31:17,479
Speaker 2: according to this, I was going really gently, more than gently.

680
00:31:17,560 --> 00:31:20,040
Speaker 1: You know, these super massive black holes have incredible jets

681
00:31:20,040 --> 00:31:22,440
Speaker 1: of gas. Some of them you can see from almost

682
00:31:22,440 --> 00:31:25,760
Speaker 1: across the galaxy. These jets that go up and down

683
00:31:25,800 --> 00:31:28,280
Speaker 1: from the poles of the black hole. They form these quasars,

684
00:31:28,320 --> 00:31:32,560
Speaker 1: and they're super bright emissions, and these enormous structures spew

685
00:31:32,680 --> 00:31:34,480
Speaker 1: out of these black holes. But this is a little

686
00:31:34,480 --> 00:31:37,920
Speaker 1: baby galaxy with a little baby black hole that's spewing

687
00:31:37,960 --> 00:31:40,680
Speaker 1: gas out, but only at a million miles per hour.

688
00:31:40,880 --> 00:31:43,440
Speaker 1: So it's slamming into this dense gas, and they think

689
00:31:43,440 --> 00:31:46,600
Speaker 1: that's what's actually sparking the birth of all of these stars.

690
00:31:47,280 --> 00:31:48,720
Speaker 2: All right, let me see if I got this straight,

691
00:31:49,000 --> 00:31:51,840
Speaker 2: there's a black hole in the center of this dwarf galaxy.

692
00:31:51,960 --> 00:31:54,360
Speaker 2: It's sucking in stuff. That's how we know it's there

693
00:31:54,400 --> 00:31:56,400
Speaker 2: because it's sucking in stuff and as the stuff falls in,

694
00:31:56,880 --> 00:31:59,520
Speaker 2: it creates a lot of energy. So now some of

695
00:31:59,520 --> 00:32:01,760
Speaker 2: that energy that it's releasing when it's sucking that stuff

696
00:32:01,800 --> 00:32:05,640
Speaker 2: in is being shut out and that's pushing another cloud

697
00:32:05,640 --> 00:32:09,280
Speaker 2: of gas into a third cloud of gas. Is that's

698
00:32:09,320 --> 00:32:13,640
Speaker 2: kind of what's happening, Like it's actually shooting radiation, not gas,

699
00:32:13,840 --> 00:32:17,040
Speaker 2: but that radiation is pushing one cloud of gas into

700
00:32:17,040 --> 00:32:19,440
Speaker 2: another cloud of gas around the black hole at a

701
00:32:19,480 --> 00:32:22,280
Speaker 2: million miles per second forever.

702
00:32:22,880 --> 00:32:25,280
Speaker 1: A million mile per hour. Burps of gas into the

703
00:32:25,280 --> 00:32:28,920
Speaker 1: stellar nursery are sparking the birth of new stars in

704
00:32:29,000 --> 00:32:30,080
Speaker 1: this dwarf galaxy.

705
00:32:30,200 --> 00:32:32,200
Speaker 2: But the gas is not coming from the black hole,

706
00:32:32,360 --> 00:32:34,959
Speaker 2: right The black hole is just pushing the gas that's

707
00:32:34,960 --> 00:32:37,840
Speaker 2: already there. Or is it like accelerating, you know, you

708
00:32:37,880 --> 00:32:39,560
Speaker 2: know what I mean, like slinging it around and then

709
00:32:39,560 --> 00:32:42,320
Speaker 2: pushing into a cloud of gas. Or is it just

710
00:32:42,480 --> 00:32:45,880
Speaker 2: emitting radiation and that's pushing one cloud into another cloud.

711
00:32:46,160 --> 00:32:48,080
Speaker 1: It's a little bit of both. The gas is heated

712
00:32:48,160 --> 00:32:50,600
Speaker 1: up from the radiation from the black hole, and that

713
00:32:50,680 --> 00:32:53,440
Speaker 1: helps it swirl around really really fast, and some of

714
00:32:53,480 --> 00:32:57,200
Speaker 1: it slams into this stellar nursery, this cocoon of gas

715
00:32:57,200 --> 00:32:59,800
Speaker 1: that exists already in the galaxy. And so it's just

716
00:33:00,160 --> 00:33:02,479
Speaker 1: like depositing a bunch of energy there, but doing it

717
00:33:02,480 --> 00:33:05,960
Speaker 1: gently enough not to overheat this nursery. It seems to

718
00:33:06,000 --> 00:33:08,160
Speaker 1: be like really right on the edge there.

719
00:33:08,080 --> 00:33:11,680
Speaker 2: But pushing it just enough so that it creates better

720
00:33:11,720 --> 00:33:14,160
Speaker 2: conditions for star formation. Is that the idea, like you're

721
00:33:14,200 --> 00:33:17,240
Speaker 2: like compressing the gas making it denser, or is it

722
00:33:17,280 --> 00:33:20,800
Speaker 2: that it's causing the ripples that you know you need

723
00:33:20,840 --> 00:33:22,360
Speaker 2: to like jump start a start.

724
00:33:22,400 --> 00:33:24,280
Speaker 1: Yeah, it could be either. We have lots of different

725
00:33:24,320 --> 00:33:28,040
Speaker 1: models of star formation. You know, imagine like taking something

726
00:33:28,080 --> 00:33:30,360
Speaker 1: and needing to compress it, but just enough, and if

727
00:33:30,360 --> 00:33:32,640
Speaker 1: you squeeze too hard, it's going to blow up essentially,

728
00:33:33,120 --> 00:33:35,400
Speaker 1: And so this is a really delicate operation. You know,

729
00:33:35,480 --> 00:33:39,720
Speaker 1: star formation is surprisingly fragile. It's incredible how many stars

730
00:33:39,720 --> 00:33:42,000
Speaker 1: have been born in the universe given how difficult it

731
00:33:42,160 --> 00:33:45,320
Speaker 1: is to arrange the conditions for stars to come together.

732
00:33:45,600 --> 00:33:48,880
Speaker 2: Mmmm. Interesting. All right, Well, let's dig into the details

733
00:33:48,880 --> 00:33:51,240
Speaker 2: of what's going on here and maybe what it means

734
00:33:51,280 --> 00:33:55,320
Speaker 2: about what we know about star formations and black holes.

735
00:33:55,680 --> 00:34:10,680
Speaker 2: But first, let's take another quick break. All right, we're

736
00:34:10,680 --> 00:34:16,160
Speaker 2: talking about black holes forming stars, and specifically there's a

737
00:34:16,360 --> 00:34:21,560
Speaker 2: dwarf galaxy nearby sort of nearby us called Henis, where

738
00:34:21,760 --> 00:34:23,360
Speaker 2: there seems to be a black hole in the middle

739
00:34:23,360 --> 00:34:26,359
Speaker 2: of that dwarf galaxy, but it's also got a lot

740
00:34:26,360 --> 00:34:29,440
Speaker 2: of gas around it, and somehow the black hole is

741
00:34:29,560 --> 00:34:32,480
Speaker 2: helping the cloud of gas form new stars, or at

742
00:34:32,560 --> 00:34:34,480
Speaker 2: least that's the idea, right mm hmm.

743
00:34:34,640 --> 00:34:37,439
Speaker 1: And one thing that's really fascinating about this black hole

744
00:34:37,560 --> 00:34:40,600
Speaker 1: is that it's not really at the center necessarily. These

745
00:34:40,680 --> 00:34:44,440
Speaker 1: dwarf galaxies are not as like organized as big old

746
00:34:44,560 --> 00:34:48,800
Speaker 1: galaxies that form really nice spirals. They're more like fuzzy blobs.

747
00:34:48,880 --> 00:34:51,520
Speaker 1: And the black hole here is not associated with like

748
00:34:51,600 --> 00:34:55,920
Speaker 1: any bulge or any other like well defined nucleus. You know.

749
00:34:55,960 --> 00:34:58,520
Speaker 1: The whole theory of like black hole formation is that

750
00:34:58,560 --> 00:35:01,400
Speaker 1: they're made from stars, and they live at the very center,

751
00:35:01,560 --> 00:35:03,480
Speaker 1: the dense place, and so they gobble up a bunch

752
00:35:03,520 --> 00:35:05,279
Speaker 1: of stars and get bigger and bigger and bigger. This

753
00:35:05,320 --> 00:35:07,840
Speaker 1: one's a bit of a puzzle because it's not sitting

754
00:35:07,880 --> 00:35:10,840
Speaker 1: at the center or like associated with the densest place

755
00:35:10,960 --> 00:35:12,240
Speaker 1: in this dwarf galaxy.

756
00:35:12,920 --> 00:35:14,759
Speaker 2: And you can actually look up a picture of this

757
00:35:14,880 --> 00:35:17,880
Speaker 2: dwarf galaxy, right, you spell it h E and I

758
00:35:18,120 --> 00:35:22,480
Speaker 2: ze two dash ten and there are pictures of it online, right.

759
00:35:22,400 --> 00:35:24,839
Speaker 1: Yeah, they're pictures of it, and you can see red

760
00:35:24,880 --> 00:35:28,279
Speaker 1: stars and blue stars and stripes of gas and all

761
00:35:28,280 --> 00:35:30,200
Speaker 1: sorts of stuff. It's a bit of a blob. I mean,

762
00:35:30,239 --> 00:35:32,439
Speaker 1: would you say this is a cute galaxy for Yeah?

763
00:35:32,480 --> 00:35:35,040
Speaker 2: Yeah, all babies are blobs. That's kind of what makes

764
00:35:35,080 --> 00:35:36,800
Speaker 2: them cute. You're blobby.

765
00:35:36,920 --> 00:35:38,600
Speaker 1: Some of them look sort of like Winston Churchill. I

766
00:35:38,600 --> 00:35:40,440
Speaker 1: don't know how cute that is, though. I mean, I'm

767
00:35:40,440 --> 00:35:42,080
Speaker 1: sure your babies are all cute, dear.

768
00:35:41,960 --> 00:35:44,520
Speaker 2: Listeners, and I'm sure all of you Winston Churchill's out

769
00:35:44,520 --> 00:35:46,280
Speaker 2: there are also cute.

770
00:35:48,560 --> 00:35:51,800
Speaker 1: How many Winston Churchills are listening to the podcast right now?

771
00:35:52,200 --> 00:35:55,640
Speaker 2: You never know. It's a big universe. You never know,

772
00:35:55,880 --> 00:35:57,919
Speaker 2: or you might be married to Winston Churchill, or maybe

773
00:35:57,920 --> 00:35:59,440
Speaker 2: you were married to Winston Churchill.

774
00:36:00,800 --> 00:36:02,000
Speaker 1: This is getting pretty surreal.

775
00:36:02,120 --> 00:36:04,759
Speaker 2: We just still want to insult any Winston Churchills or

776
00:36:04,800 --> 00:36:06,040
Speaker 2: any Winstons at.

777
00:36:05,880 --> 00:36:08,600
Speaker 1: All, or really anybody. We're not out to insult.

778
00:36:08,280 --> 00:36:12,399
Speaker 6: Anybody, especially not this galaxy, which is a cute little

779
00:36:12,480 --> 00:36:15,360
Speaker 6: dwarf galaxy, but doesn't sort of fit your mental image

780
00:36:15,400 --> 00:36:17,719
Speaker 6: of a galaxy because it's a little dwarf galaxy, right,

781
00:36:17,800 --> 00:36:19,880
Speaker 6: it hasn't it formed its big boy structure or it's

782
00:36:19,920 --> 00:36:21,320
Speaker 6: big girl structure.

783
00:36:21,239 --> 00:36:23,000
Speaker 1: And so it's a bit of a blob, and its

784
00:36:23,239 --> 00:36:25,600
Speaker 1: massive black hole is not like right at the heart

785
00:36:25,640 --> 00:36:25,879
Speaker 1: of it.

786
00:36:26,040 --> 00:36:29,879
Speaker 2: Now, is this a galaxy, this dwarf galaxy unusual or

787
00:36:30,000 --> 00:36:32,719
Speaker 2: is this just like one where we found that we

788
00:36:32,800 --> 00:36:34,480
Speaker 2: know for sure it has a black hole in it

789
00:36:34,560 --> 00:36:37,640
Speaker 2: and where we seeing some interesting star formation, or is

790
00:36:37,719 --> 00:36:40,720
Speaker 2: Henny's pretty typical of dwarf galaxies and we just happened

791
00:36:40,760 --> 00:36:43,200
Speaker 2: to pick this one because it's convenient to study.

792
00:36:43,320 --> 00:36:45,720
Speaker 1: I think it's the latter. It's one that we have studied,

793
00:36:45,760 --> 00:36:48,600
Speaker 1: people have identified the black hole in it. It's taken

794
00:36:48,600 --> 00:36:50,880
Speaker 1: a while to figure that out. There was like papers

795
00:36:50,880 --> 00:36:53,160
Speaker 1: for years about whether this is a black hole or

796
00:36:53,200 --> 00:36:56,040
Speaker 1: something else. It's not always easy to identify a black

797
00:36:56,040 --> 00:36:59,080
Speaker 1: hole in a distant galaxy, especially a dwarf galaxy. So

798
00:36:59,160 --> 00:37:02,600
Speaker 1: dwarf galaxies having always got as much attention as normal

799
00:37:02,680 --> 00:37:06,120
Speaker 1: big Mama and Papa galaxies have because they're harder to see,

800
00:37:06,200 --> 00:37:08,759
Speaker 1: you know, they're fainter. But recently we've understood that they're

801
00:37:08,920 --> 00:37:12,960
Speaker 1: really great laboratory for understanding the formation of galaxies and

802
00:37:13,120 --> 00:37:16,120
Speaker 1: dark matter and black holes. We had a whole episode

803
00:37:16,120 --> 00:37:19,280
Speaker 1: recently about the physics of dwarf galaxies, so it's really

804
00:37:19,320 --> 00:37:21,040
Speaker 1: just sort of like taking off. It's like a whole

805
00:37:21,040 --> 00:37:24,279
Speaker 1: new field within astronomy, the study of dwarf galaxies, and

806
00:37:24,320 --> 00:37:26,239
Speaker 1: so this is one of the first ones. We don't

807
00:37:26,280 --> 00:37:29,520
Speaker 1: really know the general properties of dwarf galaxies very well

808
00:37:29,560 --> 00:37:31,400
Speaker 1: because a lot of them are missing. You know, we

809
00:37:31,640 --> 00:37:33,759
Speaker 1: expect in our simulations to see lots and lots of

810
00:37:33,800 --> 00:37:36,719
Speaker 1: dwarf galaxies sometimes around big galaxies, and we don't see

811
00:37:36,840 --> 00:37:39,000
Speaker 1: very many. And we don't always know if that's because

812
00:37:39,000 --> 00:37:41,759
Speaker 1: our simulations are wrong, or we just can't see them

813
00:37:41,840 --> 00:37:45,160
Speaker 1: because they're so faint, or they're mostly dark matter or what. So.

814
00:37:45,600 --> 00:37:48,680
Speaker 1: Lots of big open questions about dwarf galaxies. This is

815
00:37:48,760 --> 00:37:50,480
Speaker 1: just one that we happen to study recently.

816
00:37:51,239 --> 00:37:53,400
Speaker 2: Okay, now, as you were saying, this black hole in

817
00:37:53,440 --> 00:37:56,400
Speaker 2: the middle of Hennis that the dwarf galaxy is spouting

818
00:37:56,400 --> 00:37:59,040
Speaker 2: out a jet of gas or a jet of radiation.

819
00:37:59,640 --> 00:38:03,520
Speaker 2: And sometimes black holes don't spout out radiation like that,

820
00:38:03,600 --> 00:38:06,960
Speaker 2: They just suck stuff in, and sometimes they shoot stuff

821
00:38:07,000 --> 00:38:10,960
Speaker 2: out so violently that it pushes everything away and disrupts

822
00:38:11,000 --> 00:38:14,800
Speaker 2: any possibility of stars forming. But this one seems to

823
00:38:14,840 --> 00:38:17,799
Speaker 2: be like just in the right Goldilogs situation here, where

824
00:38:17,800 --> 00:38:20,799
Speaker 2: it's shooting out radiation, but it's not doing it in

825
00:38:20,880 --> 00:38:22,880
Speaker 2: such a way that it disrupts things. In fact, it's

826
00:38:22,960 --> 00:38:25,960
Speaker 2: sort of doing it gently enough that it's maybe helping

827
00:38:26,160 --> 00:38:29,560
Speaker 2: more stars form in this dwarf galaxy. Do we know why,

828
00:38:29,680 --> 00:38:30,359
Speaker 2: We don't know why.

829
00:38:30,400 --> 00:38:33,600
Speaker 1: And in general, we'd like to understand more about how

830
00:38:33,719 --> 00:38:36,759
Speaker 1: black holes form in these galaxies and whether they are

831
00:38:36,800 --> 00:38:39,000
Speaker 1: linked to the mass of the galaxies. In lots of

832
00:38:39,080 --> 00:38:41,200
Speaker 1: cases we see a connection between the mass of the

833
00:38:41,200 --> 00:38:43,640
Speaker 1: black hole and the mass of the galaxy, where bigger

834
00:38:43,680 --> 00:38:46,399
Speaker 1: galaxies have bigger black holes, but also sometimes we don't

835
00:38:46,400 --> 00:38:49,040
Speaker 1: see a connection. And we've recently talked about a paper

836
00:38:49,080 --> 00:38:51,520
Speaker 1: that saw that black holes the hearts of galaxies grow

837
00:38:51,600 --> 00:38:55,040
Speaker 1: faster than the galaxies do, suggesting that they're maybe not

838
00:38:55,200 --> 00:38:57,840
Speaker 1: just eating mass that there's some other weird thing connected

839
00:38:57,880 --> 00:39:00,920
Speaker 1: to dark energy. Right, it's a big question of like

840
00:39:00,960 --> 00:39:03,680
Speaker 1: the relationship between the mass of a black hole and

841
00:39:03,760 --> 00:39:06,160
Speaker 1: the mass of the galaxy that it's in. It's not

842
00:39:06,360 --> 00:39:10,399
Speaker 1: something that we understand, especially for these super massive black holes,

843
00:39:10,440 --> 00:39:12,560
Speaker 1: these ones that are bigger than just like the endpoint

844
00:39:12,600 --> 00:39:14,440
Speaker 1: of a single star. So it's a great way to

845
00:39:14,480 --> 00:39:17,480
Speaker 1: study not just star formation, but also to understand how

846
00:39:17,560 --> 00:39:20,279
Speaker 1: black holes get their start, right, because again, this is

847
00:39:20,320 --> 00:39:23,040
Speaker 1: not a super massive galaxy with a super massive black hole,

848
00:39:23,040 --> 00:39:25,160
Speaker 1: and this is like looking back to its childhood to

849
00:39:25,239 --> 00:39:27,400
Speaker 1: understand how it got so big so fast.

850
00:39:28,239 --> 00:39:31,160
Speaker 2: We're looking at this baby galaxy as a way to

851
00:39:31,200 --> 00:39:33,320
Speaker 2: study baby galaxy development kind.

852
00:39:33,200 --> 00:39:35,880
Speaker 1: Of yeah, exactly. And this one is exciting because it

853
00:39:36,000 --> 00:39:39,920
Speaker 1: sort of hints towards this primordial black hole theory. You know,

854
00:39:40,000 --> 00:39:42,759
Speaker 1: this idea that maybe black holes, the ones become monsters,

855
00:39:42,760 --> 00:39:45,000
Speaker 1: that the hearts of galaxies didn't form the way we

856
00:39:45,040 --> 00:39:47,759
Speaker 1: described earlier, just like a single star that collapses and

857
00:39:47,760 --> 00:39:49,920
Speaker 1: then gradually eats stuff. Maybe they got a boost, they

858
00:39:50,000 --> 00:39:53,279
Speaker 1: got like a head start by being formed very early on,

859
00:39:53,440 --> 00:39:57,879
Speaker 1: before even hydrogen was formed. These primordial black holes which

860
00:39:57,920 --> 00:40:00,319
Speaker 1: then just grew rapidly. The idea here or is that

861
00:40:00,360 --> 00:40:03,080
Speaker 1: maybe that's the reason it's not like right at the

862
00:40:03,080 --> 00:40:05,720
Speaker 1: heart of the galaxy, where like there's the densest blob

863
00:40:05,800 --> 00:40:08,040
Speaker 1: of matter. Maybe that's why it's sort of like offset

864
00:40:08,120 --> 00:40:10,279
Speaker 1: a little bit, because it was seated by a primordial

865
00:40:10,360 --> 00:40:13,000
Speaker 1: black hole. Not just like the formation of a black

866
00:40:13,040 --> 00:40:15,960
Speaker 1: hole at the densest spot in the galaxy.

867
00:40:16,080 --> 00:40:18,759
Speaker 2: Already just moved to the suburbs, you know, for quieter light.

868
00:40:20,360 --> 00:40:21,480
Speaker 2: That's what makes it so gentle.

869
00:40:22,120 --> 00:40:23,920
Speaker 1: But this is a young black hole, right It's going

870
00:40:24,000 --> 00:40:25,480
Speaker 1: to want to be at the heart of the action.

871
00:40:25,640 --> 00:40:28,080
Speaker 1: It's going to move into the city, right where all

872
00:40:28,080 --> 00:40:28,879
Speaker 1: the clubs stay out.

873
00:40:29,840 --> 00:40:33,000
Speaker 2: I say that all young black holes are hipster black hole.

874
00:40:33,760 --> 00:40:35,880
Speaker 2: I thought Brooklyn was where it's at, not Manhattan.

875
00:40:35,920 --> 00:40:37,319
Speaker 1: I mean, maybe this is a black hole with an

876
00:40:37,360 --> 00:40:38,480
Speaker 1: old soul. I don't know.

877
00:40:38,840 --> 00:40:41,480
Speaker 2: Yeah, you go, But I guess the point is that

878
00:40:41,520 --> 00:40:44,680
Speaker 2: this black hole in this dwarf galaxy is actually helping

879
00:40:44,800 --> 00:40:47,920
Speaker 2: make stars, right Like, without this black hole, this dwarf

880
00:40:47,920 --> 00:40:50,239
Speaker 2: galaxy wouldn't be making as many stars. Now, is the

881
00:40:50,280 --> 00:40:53,239
Speaker 2: idea that this is happening all over the galaxy or

882
00:40:53,560 --> 00:40:56,040
Speaker 2: this is like a weird situation like, could it be

883
00:40:56,160 --> 00:40:59,080
Speaker 2: that our star was somehow aided by a black hole

884
00:40:59,160 --> 00:41:02,879
Speaker 2: or that black hole holes are helping stars form all

885
00:41:02,880 --> 00:41:06,040
Speaker 2: over the our galaxy and in other galaxies.

886
00:41:06,160 --> 00:41:08,799
Speaker 1: It's certainly possible, and what it does is paint a

887
00:41:08,840 --> 00:41:12,800
Speaker 1: picture of star formation is more complex than we previously imagined.

888
00:41:13,120 --> 00:41:14,880
Speaker 1: You know, we had a sort of simple model before

889
00:41:15,000 --> 00:41:17,440
Speaker 1: these clouds of gas which then collapse, and now we

890
00:41:17,520 --> 00:41:20,440
Speaker 1: understand that creating the conditions for a star formation is

891
00:41:20,440 --> 00:41:22,960
Speaker 1: tricky and lots of different processes out there in the

892
00:41:23,040 --> 00:41:25,879
Speaker 1: universe can play a role, probably more than just black

893
00:41:25,920 --> 00:41:28,520
Speaker 1: hole formation. Other things we haven't even thought about might

894
00:41:28,520 --> 00:41:31,799
Speaker 1: trigger star collapse or end star collapse. So this is

895
00:41:31,800 --> 00:41:34,680
Speaker 1: something that astronomers are really digging into in detail now,

896
00:41:34,960 --> 00:41:37,080
Speaker 1: finding regions of the universe where stars are being formed,

897
00:41:37,120 --> 00:41:39,719
Speaker 1: rapidly finding regions of the universe where stars are not

898
00:41:39,760 --> 00:41:42,800
Speaker 1: being formed, trying to understand all the effects at play.

899
00:41:43,200 --> 00:41:45,680
Speaker 1: And it's a very complex situation. It's not like the

900
00:41:45,760 --> 00:41:48,240
Speaker 1: kind of thing you can study in isolation and say

901
00:41:48,440 --> 00:41:50,080
Speaker 1: I'm just going to take a blob of gas and

902
00:41:50,120 --> 00:41:52,880
Speaker 1: think about how it works. It's something that really depends

903
00:41:52,880 --> 00:41:55,400
Speaker 1: on everything that's going on in the neighborhood. You know,

904
00:41:55,440 --> 00:41:58,400
Speaker 1: you have to understand not just nearby black holes emitting

905
00:41:58,480 --> 00:42:01,359
Speaker 1: radiation that might coax your stars to forming or might

906
00:42:01,520 --> 00:42:04,760
Speaker 1: quash their ability to form stars. You also have to understand,

907
00:42:04,800 --> 00:42:07,960
Speaker 1: like the dark matter halo for this galaxy, is the

908
00:42:08,040 --> 00:42:11,120
Speaker 1: dark matter halo getting too big so that it's pulling

909
00:42:11,160 --> 00:42:14,719
Speaker 1: in too much gas from the intergalactic medium, which then

910
00:42:14,800 --> 00:42:17,080
Speaker 1: like heats up all the gas in the galaxy and

911
00:42:17,080 --> 00:42:19,759
Speaker 1: make it stop forming stars. To understand how this works,

912
00:42:19,760 --> 00:42:22,080
Speaker 1: we're going to have to get almost everything right. And

913
00:42:22,120 --> 00:42:24,479
Speaker 1: that's the kind of problem that's really hard. You can't

914
00:42:24,520 --> 00:42:26,839
Speaker 1: like break it into pieces and isolate and think about

915
00:42:26,880 --> 00:42:28,960
Speaker 1: it all by itself. You really got to get lots

916
00:42:29,000 --> 00:42:32,399
Speaker 1: of different elements in place all at once. So it's

917
00:42:32,400 --> 00:42:34,839
Speaker 1: sort of like a big grand challenge for astronomy over

918
00:42:34,840 --> 00:42:35,920
Speaker 1: the next couple of decades.

919
00:42:37,200 --> 00:42:39,560
Speaker 2: I guess there's a lot going on here out there

920
00:42:39,560 --> 00:42:41,200
Speaker 2: in the universe, and there's a lot that could be

921
00:42:41,680 --> 00:42:44,960
Speaker 2: disrupting or influencing the formation of stars.

922
00:42:45,080 --> 00:42:46,719
Speaker 1: Yeah, exactly. And we're working on this sort of in

923
00:42:46,760 --> 00:42:49,160
Speaker 1: two directions. On one hand, we're like looking out there

924
00:42:49,160 --> 00:42:51,040
Speaker 1: to see what's going on, and on the other hand,

925
00:42:51,239 --> 00:42:54,440
Speaker 1: we're building models, we're doing calculations to predict what we

926
00:42:54,520 --> 00:42:57,920
Speaker 1: should see. Right, Scientias progresses along these two fronts, the

927
00:42:58,040 --> 00:43:02,120
Speaker 1: experimental or observational and the theoretical. Can we explain what

928
00:43:02,160 --> 00:43:04,680
Speaker 1: we are seeing? So people working on the theoretical side

929
00:43:04,719 --> 00:43:08,200
Speaker 1: have these models, these simulations where they build little galaxies

930
00:43:08,200 --> 00:43:10,960
Speaker 1: and watch them form and measure the star formation rate

931
00:43:11,000 --> 00:43:12,279
Speaker 1: and see if they get it right. But you can

932
00:43:12,320 --> 00:43:15,520
Speaker 1: never simulate an entire universe or even entire galaxy. These

933
00:43:15,520 --> 00:43:19,160
Speaker 1: simulations are always simplified. Sometimes they for example, like only

934
00:43:19,200 --> 00:43:21,520
Speaker 1: have one kind of matter, or they ignore the dark matter,

935
00:43:21,640 --> 00:43:23,960
Speaker 1: or they ignore the non dark matter, or they ignore

936
00:43:24,000 --> 00:43:27,040
Speaker 1: the supernovas. To add all those details, all those bells

937
00:43:27,080 --> 00:43:30,000
Speaker 1: and whistles into your simulation is really complicated. So at

938
00:43:30,040 --> 00:43:31,400
Speaker 1: first we were able to do it with sort of

939
00:43:31,440 --> 00:43:34,560
Speaker 1: simplified versions, But now what we're learning is we really

940
00:43:34,600 --> 00:43:36,320
Speaker 1: got to break out all the bells and whistles to

941
00:43:36,400 --> 00:43:39,040
Speaker 1: understand star formation. It's not something where you're going to

942
00:43:39,120 --> 00:43:42,160
Speaker 1: understand it with a simple model using only one component

943
00:43:42,200 --> 00:43:44,600
Speaker 1: of the universe. It's like a whole symphony of chaos

944
00:43:44,880 --> 00:43:48,440
Speaker 1: that sometimes come together to form just the right conditions.

945
00:43:48,600 --> 00:43:50,200
Speaker 2: And sometimes there's a lot of stuff out there that

946
00:43:50,239 --> 00:43:53,200
Speaker 2: you can't see, right, like these black holes. Maybe you

947
00:43:53,239 --> 00:43:55,960
Speaker 2: didn't know it was there before, or it could confirm

948
00:43:56,000 --> 00:43:58,479
Speaker 2: that it was there. And also things like dark matter

949
00:43:58,560 --> 00:44:00,480
Speaker 2: could be influenced things that you can get in a

950
00:44:00,520 --> 00:44:03,080
Speaker 2: way that you can't see, or maybe also dark energy.

951
00:44:03,160 --> 00:44:05,320
Speaker 1: Right, Yeah, And that's why these are such fun puzzles

952
00:44:05,320 --> 00:44:07,960
Speaker 1: because you work really hard to explain them using the

953
00:44:08,000 --> 00:44:10,760
Speaker 1: pieces that you do understand, but sometimes you just can't

954
00:44:11,040 --> 00:44:13,200
Speaker 1: and you're like, well, something else is going on. Maybe

955
00:44:13,239 --> 00:44:15,359
Speaker 1: we're missing a piece of the puzzle. There's something else

956
00:44:15,440 --> 00:44:17,319
Speaker 1: going on out there we haven't figured out yet that

957
00:44:17,360 --> 00:44:19,560
Speaker 1: we need to add to our description in order to

958
00:44:19,719 --> 00:44:22,400
Speaker 1: explain what we're seeing out there in the universe. So

959
00:44:22,440 --> 00:44:25,760
Speaker 1: that's why we chase these discrepancies so hard, because sometimes

960
00:44:25,760 --> 00:44:28,719
Speaker 1: the explanation is boring. It's like, oh, you're making this approximation,

961
00:44:28,960 --> 00:44:31,319
Speaker 1: but it's actually really important, so you can't make that approximation.

962
00:44:31,360 --> 00:44:33,680
Speaker 1: You got to really do it right. But sometimes the

963
00:44:33,719 --> 00:44:37,560
Speaker 1: answer is really exciting. It's like, oops, you missed something fundamental.

964
00:44:37,800 --> 00:44:40,160
Speaker 1: There's something really big, and this is a little thread

965
00:44:40,160 --> 00:44:42,919
Speaker 1: that unravels the whole story. So science is all about

966
00:44:43,000 --> 00:44:46,000
Speaker 1: chasing down these details and getting them right, not knowing

967
00:44:46,000 --> 00:44:49,000
Speaker 1: whether they're clues to a bigger mystery or just dotting

968
00:44:49,000 --> 00:44:50,000
Speaker 1: the I and crossing the T.

969
00:44:50,760 --> 00:44:53,800
Speaker 2: Yeah, and I guess it's important to sort of understand

970
00:44:53,840 --> 00:44:56,719
Speaker 2: how stars form out there in the whole universe, to

971
00:44:56,800 --> 00:44:59,600
Speaker 2: kind of maybe understand our own context, right, Like, was

972
00:44:59,640 --> 00:45:03,320
Speaker 2: our story formed in a really special or unlikely way?

973
00:45:03,520 --> 00:45:05,840
Speaker 2: Or are we just, you know, one of many many

974
00:45:05,880 --> 00:45:07,920
Speaker 2: stars out there that form in the regular way. That

975
00:45:07,960 --> 00:45:10,200
Speaker 2: would kind of tell us a little bit about how

976
00:45:10,440 --> 00:45:13,080
Speaker 2: likely it is that we're here and here to study

977
00:45:13,080 --> 00:45:13,720
Speaker 2: this kind of stuff.

978
00:45:13,800 --> 00:45:16,399
Speaker 1: Yeah, it's sort of incredible that stars form at all

979
00:45:16,480 --> 00:45:18,680
Speaker 1: in this universe. You know, so much has to go

980
00:45:18,840 --> 00:45:21,400
Speaker 1: right for stars to form, Otherwise the universe would have

981
00:45:21,520 --> 00:45:24,960
Speaker 1: just been dark forever. It's sort of incredible. And you're

982
00:45:25,000 --> 00:45:27,600
Speaker 1: right that our star is kind of unusual. Remember, most

983
00:45:27,600 --> 00:45:29,799
Speaker 1: of the stars out there in the galaxy are not

984
00:45:30,280 --> 00:45:35,000
Speaker 1: yellow stars like ours, they're cooler stars, they're red dwarf stars.

985
00:45:35,040 --> 00:45:37,719
Speaker 1: So our star already is a little bit unusual. And

986
00:45:37,760 --> 00:45:40,880
Speaker 1: of course, behind all of these questions, we're always wondering, like,

987
00:45:41,040 --> 00:45:43,319
Speaker 1: is our whole situation unusual? Is it really rare for

988
00:45:43,520 --> 00:45:46,400
Speaker 1: us to exist, or are we pretty common in the universe.

989
00:45:46,719 --> 00:45:49,600
Speaker 1: So understanding like how stars get formed in the first place,

990
00:45:49,640 --> 00:45:52,040
Speaker 1: and how you get bigger stars and little stars, that's

991
00:45:52,080 --> 00:45:54,840
Speaker 1: a whole other mystery. We don't even really understand this

992
00:45:54,960 --> 00:45:58,200
Speaker 1: initial mass function of the stars. How you get bigger

993
00:45:58,239 --> 00:46:01,360
Speaker 1: clumps and smaller clumps is part of the deeper question

994
00:46:01,440 --> 00:46:03,520
Speaker 1: to understand how we got here in the first place.

995
00:46:03,960 --> 00:46:06,520
Speaker 2: M All right, Well, at least if you don't figure

996
00:46:06,560 --> 00:46:08,200
Speaker 2: it out, it's not so bad at Lisia end up

997
00:46:08,200 --> 00:46:10,520
Speaker 2: with a lot of cute baby pictures to put up

998
00:46:10,520 --> 00:46:13,720
Speaker 2: on your fridge and your galactic fridge.

999
00:46:14,560 --> 00:46:16,120
Speaker 1: That's right. I wonder if there's a certain kind of

1000
00:46:16,160 --> 00:46:19,359
Speaker 1: astronomer who likes babies, who tends to work on star

1001
00:46:19,440 --> 00:46:21,799
Speaker 1: formation because they want to look inside the windows of

1002
00:46:21,880 --> 00:46:22,960
Speaker 1: stellar nurseries.

1003
00:46:23,160 --> 00:46:25,440
Speaker 2: You mean there are physicists who don't like babies.

1004
00:46:25,800 --> 00:46:28,760
Speaker 1: There definitely are people out there who don't like babies.

1005
00:46:28,800 --> 00:46:31,120
Speaker 2: Man, not everybody has the anti baby.

1006
00:46:32,400 --> 00:46:34,520
Speaker 1: I don't know if anybody's anti baby. They might just

1007
00:46:34,520 --> 00:46:36,360
Speaker 1: be like mutual on babies.

1008
00:46:37,480 --> 00:46:40,239
Speaker 2: I see you're cool on babies exactly.

1009
00:46:40,560 --> 00:46:42,200
Speaker 1: People. You know, I could take a baby or leave

1010
00:46:42,239 --> 00:46:45,200
Speaker 1: a baby I'm not sure. Personally, I love babies, but

1011
00:46:45,320 --> 00:46:47,880
Speaker 1: you know, not everybody out there feels that way anyway.

1012
00:46:48,000 --> 00:46:51,439
Speaker 1: Star babies and galaxy babies are also super fun because

1013
00:46:51,440 --> 00:46:54,360
Speaker 1: they teach us about where' staharson galaxies come from.

1014
00:46:54,440 --> 00:46:56,080
Speaker 2: All right, Well, hopefully the next time you look up

1015
00:46:56,080 --> 00:46:58,279
Speaker 2: at the night sky you get to see maybe the

1016
00:46:58,320 --> 00:47:00,919
Speaker 2: birth of any star. It's possible to be looking other

1017
00:47:01,080 --> 00:47:03,920
Speaker 2: and into space and then suddenly a new star is.

1018
00:47:03,880 --> 00:47:06,640
Speaker 1: Born, because this guy and the cosmos in the universe

1019
00:47:06,760 --> 00:47:09,759
Speaker 1: are constantly changing, and we are keeping our eyeballs on

1020
00:47:09,840 --> 00:47:12,160
Speaker 1: it to learn as much as we can from everything

1021
00:47:12,280 --> 00:47:12,680
Speaker 1: it does.

1022
00:47:12,920 --> 00:47:15,680
Speaker 2: And if you remember anything from this conversation, just remember

1023
00:47:16,400 --> 00:47:19,480
Speaker 2: Baby Star Stars, Stars and Stars Star Baby.

1024
00:47:19,200 --> 00:47:22,759
Speaker 1: Start for his new viral hit.

1025
00:47:22,960 --> 00:47:25,560
Speaker 2: We hope you enjoyed that. Thanks for joining us, See

1026
00:47:25,600 --> 00:47:26,120
Speaker 2: you next time.

1027
00:47:33,880 --> 00:47:36,680
Speaker 1: Thanks for listening, and remember that Daniel and Jorge Explain

1028
00:47:36,760 --> 00:47:40,759
Speaker 1: the Universe is a production of iHeartRadio. For more podcasts

1029
00:47:40,760 --> 00:47:45,400
Speaker 1: from iHeartRadio, visit the iHeartRadio app, Apple Podcasts, or wherever

1030
00:47:45,480 --> 00:47:47,200
Speaker 1: you listen to your favorite shows.